The invention relates to a core assembly comprising an actuator for during operation advancing and retracting at least one core into and from a mould cavity in a mould consisting of two mould halves clamped onto each their platen of an injection moulding-machine, whereby the actuator is connected to a core-carrier for carrying the at least one core.
The invention also relates to an injection moulding-machine comprising said core assembly and a method of manufacturing moulded products by utilizing the moulding-machine.
Injection moulding is a popular and efficient technique to mass-produce plastic products for various applications. There are few limitations as to the shape and complexity of injection moulded products. Accordingly, recent decades have seen an ever-increasing number of custom-shaped moulded products.
Many of those products are formed with openings, undercuts or the like formed in the side of the products. Core assemblies therefore is required for imparting the cores to be moved to and fro into a direction forming an angle with the direction in which plastic is injected into the mould cavity in the mould.
A known core assembly of this kind comprises a cam pin arrangements where an angular pin disposed in the movable mould half is used for moving a cam slide carrying a core. Upon opening and closing of the mould, the angular movement of the cam pin translates into sliding motion of the cam slide and the attached core.
An inherent drawback of this approach is that it depends on an optimal fit of components including the mould halves, which often are subject to some compression and expansion during operation. Also, cam pins may be prone to deflection and displacement owing to the force component acting in the mould clamping direction. This may increase maintenance efforts and costs. Also, the motion of a cam slide sliding in a guideway formed in a mould half cannot be performed with the required accuracy.
Other known core assemblies of this kind are arranged for moving the cam slide independently of the clamping motion of the mould halves. These assemblies include actuators as e.g. hydraulic working cylinders attached to the cam slide and the mould for moving the slide with the core. It is however difficult to connect the actuators to both the cam slide and the mould.
An attempt to solve this problem is known from the PCT application WO 2008/015274 A1. The core assembly comprises also in this case a guideway and a slide, which slidingly is mounted onto the guideway and an actuator in form of a hydraulic working cylinder attached to the slide. The guideway is however attached to a clamping arrangement on the stationary platen of an injection moulding-machine whereby effectively is prevented that the hydraulic working cylinder need to be attached to the respective mold half. The guideway can however in this way not continuously be sufficiently exact orientated in relation to the required motion direction of the core resulting in that the product can be incorrectly moulded.